It has been known for many years that asphaltic (bituminous) compositions containing up to 10 percent by weight of rubber and up to 10 percent by weight of sulfur can be prepared. While these compositions containing natural or synthetic alkadiene homo- or copolymers still having olefinic double bonds possess desirable properties, they also show an undesirable effect when held at elevated temperatures over a prolonged period of time. For instance in a commercial paving operation, an increase in viscosity occurs owing to the crosslinking of the unsaturated rubber with the sulfur.
It has been discovered according to this invention that this increase in viscosity, which is undesirable for many paving and coating operations, can be eliminated by employing hydrogenated, saturated diene-vinylarene copolymers as the elastomer component. Because of the essential absence of crosslinking reactions between sulfur and hydrogenated diene-vinylarene copolymers, such rubberized asphalt compositions can be loaded with much higher sulfur levels than have been previously reported, resulting in improved physical properties.
Accordingly, an object of this invention is to provide asphalt compositions exhibiting improved physical properties.
A further object of this invention is to provide asphalt compositions that can be readily prepared resulting in products having improved physical properties.
A further object of this invention is to provide asphalt compositions having improved high temperature viscosity stability and improved tensile properties.
Other objects, aspects as well as the several advantages of the invention will be apparent to those skilled in the art upon reading the specification and the appended claims.